X.] SENSATION AND THE SENSIFEROUS ORGANS. 263 



and effect may not both be effects of a common cause 

 that also is as safe from refutation, if as incapable 

 of demonstration, as the other two. 



In my own opinion, neither of these speculations 

 can be regarded seriously as anything but a more or 

 less convenient working hypothesis. But, if I must 

 choose among them, I take the " law of parcimony " 

 for my guide, and select the simplest namely, that 

 the sensation is the direct effect of the mode of 

 motion of the sensorium. It may justly be said that 

 this is not the slightest explanation of sensation ; but 

 then am I really any the wiser, if I say that a sensa- 

 tion is an activity (of which I know nothing) of a 

 substance of mind (of which also I know nothing) ? 

 Or, if I say that the Deity causes the sensation to 

 arise in my mind immediately after He has caused 

 the particles of the sensorium to move in a certain 

 way, is anything gained ? In truth, a sensation, as 

 we have already seen, is an intuition a part of 

 immediate knowledge. As such, it is an ultimate fact 

 and inexplicable ; and all that we can hope to find 

 out about it, and that indeed is worth finding out, is 

 its relation to other natural facts. That relation 

 appears to me to be sufficiently expressed, for all 

 practical purposes, by saying that sensation is the 

 invariable consequent of certain changes in the sen- 

 sorium or, in other words, that, so far as we know, 

 the change in the sensorium is the cause of the 

 sensation. 



I permit myself to imagine that the untutored, if 

 noble, savage of " common sense " who has been misled 



